EP3213303A1 - Authentication systems, authentication devices, and methods for authenticating a value article - Google Patents
Authentication systems, authentication devices, and methods for authenticating a value articleInfo
- Publication number
- EP3213303A1 EP3213303A1 EP15856056.5A EP15856056A EP3213303A1 EP 3213303 A1 EP3213303 A1 EP 3213303A1 EP 15856056 A EP15856056 A EP 15856056A EP 3213303 A1 EP3213303 A1 EP 3213303A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- signal
- light source
- radiation
- detected radiation
- exciting light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
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- 230000000903 blocking effect Effects 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 9
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- 238000001914 filtration Methods 0.000 claims description 6
- 238000001514 detection method Methods 0.000 description 6
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- 230000003321 amplification Effects 0.000 description 4
- 238000003199 nucleic acid amplification method Methods 0.000 description 4
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 description 3
- KXNLCSXBJCPWGL-UHFFFAOYSA-N [Ga].[As].[In] Chemical compound [Ga].[As].[In] KXNLCSXBJCPWGL-UHFFFAOYSA-N 0.000 description 3
- 230000001351 cycling effect Effects 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 230000000875 corresponding effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- WPYVAWXEWQSOGY-UHFFFAOYSA-N indium antimonide Chemical compound [Sb]#[In] WPYVAWXEWQSOGY-UHFFFAOYSA-N 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- ZXEYZECDXFPJRJ-UHFFFAOYSA-N $l^{3}-silane;platinum Chemical compound [SiH3].[Pt] ZXEYZECDXFPJRJ-UHFFFAOYSA-N 0.000 description 1
- 229910000673 Indium arsenide Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000007850 fluorescent dye Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- RPQDHPTXJYYUPQ-UHFFFAOYSA-N indium arsenide Chemical compound [In]#[As] RPQDHPTXJYYUPQ-UHFFFAOYSA-N 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 229940056932 lead sulfide Drugs 0.000 description 1
- 229910052981 lead sulfide Inorganic materials 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229910021339 platinum silicide Inorganic materials 0.000 description 1
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- 229920006395 saturated elastomer Polymers 0.000 description 1
- GGYFMLJDMAMTAB-UHFFFAOYSA-N selanylidenelead Chemical compound [Pb]=[Se] GGYFMLJDMAMTAB-UHFFFAOYSA-N 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G07—CHECKING-DEVICES
- G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
- G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
- G07D7/06—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using wave or particle radiation
- G07D7/12—Visible light, infrared or ultraviolet radiation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/64—Fluorescence; Phosphorescence
-
- G—PHYSICS
- G07—CHECKING-DEVICES
- G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
- G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
- G07D7/06—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using wave or particle radiation
- G07D7/12—Visible light, infrared or ultraviolet radiation
- G07D7/121—Apparatus characterised by sensor details
Definitions
- the technical field generally relates to systems, devices, and methods for authenticating a value article. More particularly, the technical field relates to systems, devices, and methods for authenticating value articles using an optical feature of the value article.
- BACKGROUND [0003] In many applications, it is necessary to distinguish an original article from a copy or counterfeit to validate the original article. An original article that includes an authenticating feature can be validated in many ways.
- Some methods involve visible (i.e., overt) authenticating features that are disposed on or incorporated into the article, such as a hologram on a credit card, an embossed image or watermark on a bank note, a security foil, a security ribbon, colored threads or colored fibers within a bank note, or a floating and/or sinking image on a passport. While these features are easy to detect with the eye and may not require equipment for authentication, these overt features are easily identified by a would-be forger and/or counterfeiter. As such, in addition to overt features, hidden (i.e. covert) features may be incorporated in original articles.
- covert features include invisible fluorescent fibers, chemically sensitive stains, and taggants such as luminescent pigments or fluorescent dyes that are incorporated into the substrate of the article.
- taggants such as luminescent pigments or fluorescent dyes that are incorporated into the substrate of the article.
- small authentication devices generally include the exciting light source and the photodetector in such close proximity that light produced by the exciting light source enters the photodetector via strong scatter from an article under interrogation. Intensity of the light from the exciting light source is generally many orders of magnitude higher than intensity of emissions from the taggants. While opticalfilters are generally employed so that the photodetector is not saturated with too much light from the exciting light source, it is difficult to effectively block light produced directly by the exciting light source while still allowing passage of emitted radiation from the taggants.
- excitation sources such as LEDs exhibit emission very far from their primary emission spectral range and that emission can be significant and within the passbands of the opticalfilters. While it is possible to further block light produced by the exciting light source by employing a thin film dielectric stack filter such as a band pass or a long pass filter, there may still be some undesired level of leakage that remains within the desired pass band of the filter system that is not related to the emitted radiation from the taggants. A number of systems would essentially be fooled by the large amount of signal within the required detection spectral range. Further, many taggants exhibit an overlap in emission wavelength with light produced by the exciting light source such that the overlapping wavelengths cannot be blocked while still enabling detection of the emissions from the taggant.
- a method for authenticating a value article includes providing the value article including a luminescent material.
- An exciting light source, an optical filter, a photodetector, a signal manipulation circuit, and an amplifier are provided.
- the luminescent material ofthe value article is exposed to light that is produced by the exciting light source. Radiation that includes light from the exciting light source and emitted radiation from the luminescent material is filtered using the optical filter to produce filtered radiation that includes emitted radiation from the luminescent material.
- the filtered radiation is detected using the photodetector to produce a detected radiation signal.
- an authentication device includes an exciting light source that is configured to produce light.
- An optical filter is configured to filter radiation that includes light from the exciting light source and emitted radiation from a luminescent material and to produce filtered radiation that includes emitted radiation from the luminescent material.
- a photodetector is configured to detect the filtered radiation. The photodetector produces a detected radiation signal.
- a signal manipulation circuit is configured to electronically manipulate the detected radiation signal to reduce an effect of light from the exciting light source on an authentication determination based upon the detected radiation signal.
- An amplifier is provided for amplifying the detected radiation signalafter the detected radiation signal is electronically manipulated.
- an authentication system includes an article path that has an inlet. The inlet has the capacity to receive a value article.
- An authentication device is disposed in the article path. The authentication device includes an exciting light source, an opticalfilter, a photodetector, a signal manipulation circuit, and an amplifier.
- the exciting light source is configured to produce light.
- Theoptical filter is configured to filter radiation that includes light from the exciting light source and emitted radiation from a luminescent material and to produce filtered radiation that includes emitted radiation from the luminescent material.
- the photodetector is configured to detect the filtered radiation.
- the photodetector produces a detected radiation signal.
- the signal manipulation circuit is configured to electronically manipulate the detected radiation signal to reduce an effect of light from the exciting light source on an authentication determination based on the detected radiation signal.
- the amplifier is configured to amplify the detected radiation signalafter the detected radiation signal is electronically manipulated to produce an amplified electronic signal.
- Circuitry is provided that has the capacity to convert the amplified electronic signal or data derived therefrom to an authentication output.
- a user interface is in electronic communication with the authentication device. The user interface has the capacity to communicate an authentication output to a user.
- FIG. 1 is a partial schematic view of an authentication system including an authentication device in accordance with an embodiment
- FIG.2 is a functional block diagram of the authenticationdeviceof FIG. 1 in accordance with an embodiment
- FIG.3 is a functional block diagram of another embodiment of the authentication device of FIG.1; [0013] FIG.
- FIG. 4 is a graph illustrating voltage over time for an exciting light source, an amplified radiation signal obtained from emitted radiation from luminescent material, and a squelch circuit during on/off cycling of the exciting light source and the squelch circuit;
- FIG. 5 is a graph illustrating voltage over time for an exciting light source, an amplified radiation signal obtained from emitted radiation from luminescent material, and a squelch circuit during on/off cycling of the exciting light source and the squelch circuit with two pulses of light from the exciting light source and accompanying on/off operation of the squelch circuit; and [0015] FIGS.
- FIG. 6(a)-6(c) are schematic representations of voltage over time for amplified radiation signals from luminescent material with two pulses of light from the exciting light source and accompanying on/off operation of the squelch circuit for luminescent material having a relatively short decay time (FIG. 6(b)) and for luminescent material having a relatively long decay time (FIG.6(c)).
- the following detailed description is merely exemplary in nature and is not intended to limit the systems, devices, and methods for authenticating a value article. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. [0017]
- Systems, devices, and methods for authenticating a value article are provided herein.
- the systems include an exciting light source, an opticalfilter, a photodetector, a signal manipulation circuit, and an amplifier. After exposing luminescent material on or in a value article to light produced by the exciting light source, the luminescent material charges/excites as normal since it absorbs the light from the exciting light source, and then discharges/emits with the material time decay characteristic value of“Tau”.
- the optical filter filters radiation that includes light from the exciting light source and emitted radiation from the luminescent material and produces filtered radiation that includes emitted radiation from the luminescent material and also generally includes leaked light from the exciting light source that cannot be completely filtered by the optical filter or that is reflected off of the value article.
- the combination of the leaked light and the taggant emission signal that remain in the filtered radiation are detected by the photodetector to produce a detected radiation signal.
- the detected radiation signal is electronically manipulated using the signal manipulation circuit to reduce an effect of light from the exciting light source on an authentication determination based on the detected radiation signal.
- “Electronic manipulationto reduce an effect of light from the exciting light sourceon an authentication determination based on the detected radiation signal,” as referred to herein, includes blocking of the detected radiation signal or selective attenuation of portions of the detected radiation signal that are attributable to light from the exciting light source.
- the signal manipulation circuit may be an electronic frequency filter and the exciting light source may be configured to produce modulated light, i.e., pulsed bursts of light, at a predetermined or preset modulation frequency (as an example, a pulse modulation at 20 pulses per second, for 2 milliseconds at 40 kHz modulation frequency).
- Portions of the detected radiation signal that are at the predetermined modulation frequency of the exciting light source may then be selectively attenuated with respect to desired portions of the detected radiation signal (i.e., portions of the detected radiation signal produced by emissions from the luminescent material) with the electronic frequency filter to produce a filtered electronic signal.
- the signal manipulation circuit may be a squelch circuit that effectively blocks the detected radiation signal until production of light from the exciting light source is ceased. The detected radiation signal is amplified with the amplifier after the detected radiation signal is electronically manipulatedto produce an amplified electronic signal.
- Value articles that include a luminescent material and that may be authenticated using the systems, devices, and methods described herein are not particularly limited and may include an identification card, a driver’s license, a passport, identity papers, a banknote, a check, a document, a paper, a stock certificate, a packaging component, a credit card, a bank card, a label, a seal, a coin, a token, a casino chip, a medallion, or a postage stamp.
- the luminescent material may be disposed within the value article or at the surface of the value article, provided that the luminescent material is positioned to enable absorption of light from the exciting light source and emission of radiation in a manner that enables detection.
- the value article includes a fibrous web of material that has the luminescent material disposed thereon or therein, e.g., a passport, identity papers, a banknote, a check, a document, a paper, a stock certificate, or a packaging component.
- the value article is a metal value article that has the luminescent material disposed on or near a surface thereof, e.g., a coin, a token, a casino chip, or a medallion.
- the value articles generally include a substrate, and the luminescent material may be included in a surface-applied or embedded authentication feature.
- Suitable luminescent materials are also not particularly limited provided that the luminescent materials are capable of producing a detectable emission (i.e., output radiation of relatively high spectral energy) in the infrared, visible, and/or ultraviolet portions of the electromagnetic spectrum upon excitation of the materials by appropriate external energy sources.
- a luminescent material emits radiation, the emission occurs over a discrete span of time, which may be defined by a measurable decay time constant and signal intensity level.
- Materials typically described as“fluorophors” (or“fluorescent”) exhibit very short emission decay time constants in the micro-, nano- or pico-second range.
- the authentication system 10 includes an article path 12 and an authentication device 14 disposed in the article path 12.
- the “article path” is a channel that is adapted to receive a value article 16 and to guide the value article 16 into an interrogation zone 20 of the authentication device 14.
- the article path 12 has an inlet 18, and the inlet 18 has the capacity to receive the value article 16.
- the authentication system 10 is a coin, token, casino chip, or medallion- operated machine, such as a vending machine, that is activated upon insertion of the value article 16 into the article path 12.
- the authentication system 10 may further include an electromagnetic detector 22 that has the capacity to detect an electromagnetic signature of the value article 16.
- a system processor 24 is in electronic communication with the authentication device 14, and may further be in electronic communication with the electromagnetic detector 22 when present, to render an authenticity determination of the value article 16.
- the authentication system 10 is a paper-operated machine, such as a currency counter or bill acceptor, andthe authenticity determination may be rendered on the basis of information received from the authentication device 14 alone.
- a user interface 26 may be in electronic communication with the authentication device 14, optionally through the system processor 24, and the user interface 26 has the capacity to communicate an authentication output to a user.
- the authentication device 14 includes the interrogation zone 20, whichhas the capacity to receive the value article 16 or a portion thereof that includes the luminescent material.
- the interrogation zone 20 includes a spaceover the authentication device 14 through which the value article 16 may pass, although it is to be appreciated that in other embodiments the interrogation zone 20 may have the capacity to receive only a portion of the value article 16 that includes the luminescent material. It is to be appreciated that the interrogation zone 20 may be configured in any way that allows interrogation of the luminescent material of the value article 16 by the authentication device 14. For example, in other embodiments and although not shown, the interrogation zone 20 may include a scanning window that receives the portion of the value article 16 by passing the value article 16 past the scanning window. [0021] Referring to FIG. 2, features of the authentication device 14 will now be described.
- the authentication device 14 primarily conducts interrogation of the value article 16 and generates data indicative of authenticity of the value article 16.
- the authentication device 14 includes components that enable interrogation of the value article 16 such as, but not limited to, an exciting light source 28 for exciting luminescent material of the value article 16 and a photodetector 30 configured to detect filtered radiation 43 including emitted radiation from the luminescent material after excitation.
- the exciting light source 28 and the photodetector 30 are configured for interrogation of contents of the interrogation zone 20.
- the authentication device 14 may include multiple exciting light sources 28 and multiple photodetectors 30, depending upon particular design and functionality considerations desired for the authentication device 14.
- the exciting light source 28 may include, for example, one or more low power laser diodes, LEDs, or other excitation sources.
- the exciting light source 28 is configured to produce light 40 in a modulated manner at a predetermined modulation frequency, with the modulated nature of the light used for signal filtering as described in further detail below.
- the authentication device 14 may also include an excitation source driver 27 and a light source trigger receiver 29.
- the excitation source driver 27 may be an electric power circuit that is used to power (switch on/off) and modulate the exciting light source 28 to produce light 40 in a modulated manner.
- the light source trigger receiver 29 may be present to communicate the presence of a value article 16 in the interrogation zone 20and provides the control signal to the excitation source driver 27.
- the photodetector 30 is configured to detect filtered radiation 43including emitted radiationfrom the luminescent material after excitation using the light 40 to produce a detected radiation signal 44.
- the photodetector 30 may include one or more electro- optical sensors, photodiodes, or other detection devices.
- the photodetector 30 has sensitivity within a spectral band of interest, and accordingly may detect emissions that are within that spectral band.
- the photodetector 30 may include a silicon detector, an indium-gallium-arsenide (InGaAs) detector (e.g., a telecom type or extended InGaAs), a lead-sulfide detector, a lead-selenide detector, a germanium detector, an indium-antimonide detector, an indium-arsenide detector, a platinum-silicide detector, an indium-antimonide detector, or another type of detector.
- the silicon detector is used.
- multiple photodetectors 30 may be used and configured to detect emissions within a channel corresponding to different bands of interest, and such photodetectors may be of the same or different type or class. [0024] As shown in FIG.
- the authentication device 14 may further include a power supply 32 that is in electrical communication with the exciting light source 28 and the photodetector 30, with a ground 34 provided to complete the circuit.
- an opticalfilter37 is positioned to filter radiation 42 that includes light 40 from the exciting light source 28 and emitted radiation from the luminescent material before it is provided to the photodetector 30, given that there is generally an excessive amount of reflected excitation light 40 as compared to emissions from the luminescent material and attenuation of incoming light from sources other than the luminescent material enables saturation of a detected radiation signal 44 to be avoided.
- Filtering of the radiation 42 produces filtered radiation 43 that includes emitted radiation from the luminescent material, with the filtered radiation 43 then being provided to the photodetector 30.
- the optical filter 37 may be an absorptive filter, or alternatively may be a band pass or a long pass filter that includes a combination of an absorptive filter with a dielectric thin film filter, with the dielectric thin film filter provided to further reduce the reflected excitation light 40. It is to be appreciated that multiple optical filters 37 may be employed.
- the optical filter 37 may include, for example, dye impregnated plastic that has the capacity to pass light only within a spectral band of interest.
- the optical filter 37 allows passage of filtered radiation 43 only within an emission band (i.e., a subset of the entire spectrum), although it is to be appreciated that significant portions of filtered radiation 43 passing through the optical filter 37 may be from sources other than the luminescent material and that are within band of interest.
- the optical filter 37 is generally angle-sensitive and the unwanted light that is blocked at normal incidence may actually pass through the optical filter 37 at higher or lower angles of incidence. The emissions that are not passed are actually reflected back, where the emissions can be re-scattered and can possibly pass through the optical filter 37 on another reflection.
- a signal manipulation circuit 38 is further provided as described in further detail below for electronically manipulatingthe detected radiation signal 44 to alleviate the impact of light 40 from the exciting light source 28 on an authentication determination based on the detected radiation signal 44.
- the exciting light source 28 and the photodetector 30 are configured for interrogation of contents of the interrogation zone 20 of FIG. 1.
- the value article 16 when the value article 16 includes a reflective surface (e.g., the surface of a coin, metal token, banknote, or any other surface of the value article 16 that exhibits light reflection) and due to close proximity between the exciting light source 28 and the photodetector 30, light 40 from the exciting light source 28 may be reflected off of the value article 16 and passed into the photodetector 30 as part of the filtered radiation 43, with a portion of the resulting detected radiation signal 44 generated by the light 40 from the exciting light source 28. Additionally, sunlight may pass into the photodetector30 as part of the filtered radiation 43 and result in a direct current portion (having no frequency) of the detected radiation signal 44.
- a reflective surface e.g., the surface of a coin, metal token, banknote, or any other surface of the value article 16 that exhibits light reflection
- ambient artificial light from incandescent or fluorescent light bulbs may pass into the photodetector 30 as part of the filtered radiation 43 and result in a portion of the detected radiation signal 44 having a very low frequency.
- the light 40 from the exciting light source 28 can significantly impact an authentication determination based on the detected radiation signal 44.
- the luminescent material is exposed to modulated light 40 produced by the exciting light source 28 at a predetermined modulation frequency
- the signal manipulation circuit 38 is an electronic frequency filter
- the detected radiation signal 44 is electronically manipulated by selectively attenuating portions of the detected radiation signal 44 that are at the predetermined modulation frequency of the exciting light source 28 with respect to desired portions of the detected radiation signal 44 using the electronic frequency filter 38 to produce a filtered electronic signal 46.
- the aforementioned portions of the detected radiation signal 44 can be separated from each other due to their wide difference in frequency characteristics.
- the modulation frequency of the modulated light 40 produced by the exciting light source 28 can be selectively attenuated, or reduced in amplitude, by placing attenuation filters at that frequency while amplifying the desired portions of the signal.
- the charge/discharge characteristic waveforms of the luminescent material can be converted into frequency space using a Fourier Transform. As long as the desired frequency components can be amplified to a much greater extent than the undesired frequency content, it should be possible to create a high enough signal to noise ratio for authentication.
- the desired portion of the detected radiation signal 44 from the luminescent material can be effectively isolated, even under circumstances where the emitted radiation 42 has the same wavelength band as a portion of the modulated light 40 and even under circumstances where the exciting light source 28 and the photodetector 30 are in extremely close proximity.
- all high frequency above the predetermined frequency can be attenuated.
- a band pass filter can be formed to block all frequencies outside a range (with presetting of the width and center frequency). In this case, all high frequencies are attenuated along with frequencies associated with sunlight and fluorescent lighting fixtures. Simple filters such as low pass can be prepared with operational amplifiercircuitry that isavailable for I/O devices.
- multi-stage filtering may be conducted, using one stage to attenuate high frequencies and another to attenuate low frequencies, leaving the desired portion of the detected radiation signal 44 in the filtered electronic signal 46after the detected radiation signal is electronically manipulated largely unattenuated.
- Presetting or predetermining the modulation frequency for the modulated light 40 from the exciting light source 28 and selectively attenuating portions of the detected radiation signal 44 at the predetermined modulation frequency enables effective filtering even when the emitted radiation 42 from the luminescent material has the same or an overlapping wavelength band as the modulated light 40.
- Same or overlapping wavelength bands are common when conventional exciting light sources 28 are employed, because filtering is conducted independent of wavelength.
- opticalfiltering of all light from the exciting light source 28 is generally not possible without also removing emitted radiation due to the overlapping wavelength band.
- the luminescent material exhibits a frequency response during emission of radiation therefrom.
- Frequency response of the luminescent material may be determined by applying a Fourier Transform to a time domain waveform that represents signal intensity over time. Sine curves, for example, produce a constant frequency response as derived using the Fourier Transform. Direct current, for example, produces a frequency response of 0. However, the frequency response during emission from many luminescent materials decays at a variable rate, and the frequency response is generally dependent upon the decay time. Shorter decay times generally exhibit higher frequency responses, e.g., in the kHz range, and may have a significant portion of emissions at 5kHz or greater. Longer decay times generally exhibit lower frequency responses and may have a significant portion of emissions under 500 Hz. Frequency responses for conventional luminescent materials are generally known or can be readily ascertained.
- the frequency response of the luminescent material includes the predetermined modulation frequency of the modulated light 40.
- portions of the detected radiation signal 44that are produced by the luminescent material are also attenuatedat the predetermined modulation frequency.
- the predetermined modulation frequency is chosen to avoid frequency response of the luminescent material at peak or near-peak emission intensities that are useful for detection.
- the predetermined modulation frequency is greater than about 10 kHz, such as from about 20 to about 50 kHz, or such as from about 35 to about 40 kHz.
- the predetermined modulation frequency is not particularly limited so long as emitted radiation 42 from the luminescent material can still be detected in the filtered electronic signal 46.
- the electronic frequency filter 38 may be fabricatedto attenuate direct current and/or portions of the detected radiation signal 44 that are below a threshold frequency, with the predetermined modulation frequency being greater than the threshold frequency.
- the portions of the detected radiation signal 44 that are below a threshold frequency may be those portions of the detected radiation signal 44 that are produced by ambient artificial light from incandescent or fluorescent light bulbs, which generally have frequencies below 200Hz.
- the predetermined modulation frequency is generally greater than about10 kHz, as set forth above, and represents a separate and distinct frequency that is different from those of ambient light sources.
- the filtered electronic signal 46 is amplified with the amplifier 48 to produce an amplified electronic signal 52. In embodiments and as shown in FIG.
- the electronic frequency filter 38 attenuates the portions of the detected radiation signal 44 due to the exciting light source 28 at the predetermined modulation frequency prior to amplification, with the filtered electronic signal 46 containing the desired portion of the detected radiation signal 44 and with the filtered electronic signal 46 then amplified by a separate amplifier 48.
- a separate amplifier 48 Although only a single amplifier 48 is shown in FIG. 2, it is to be appreciated that multiple stages of amplifiers 48 may be in electronic communication with the electronic frequency filter 38 for amplifying the filtered electronic signal 46.
- the electronic frequency filter 38 is coupled with the amplifier 48, i.e., the electronic frequency filter 38 and the amplifier 48 are included in the same hardware, with attenuation of the portion of the detected radiationsignal 44 at the predetermined modulation frequency due to the exciting light source 28 conducted while the desired portion of the signal is passed and amplified to produce the amplified electronic signal 52.
- the authentication device 14 may include a circuitry 50 having the capacity to convert the amplified electronic signal 52 or data derived therefrom to an authentication output.
- the circuitry 50 may include an analog to digital converter, and the amplifiedelectronic signal 52 may be passed directly to the circuitry 50 for further conversion to a digital signal that is indicative of authenticity of the value article 16.
- the circuitry 50 includes a comparator that is set at a threshold level for the amplified electronic signal 52, with the comparator producing output that goes to a logical value of“1” as long as the amplifiedelectronic signal 52 value remains above a predeterminedintensity.
- the exciting light source 28, the photodetector 30, and the electronic frequency filter 38 are disposed on a singlesubstrate 54thereby minimizing space requirements for the individual elements of the authentication device 14.
- the authentication device 14 is an integrated circuit.
- the authentication device 14 fabricated as an integrated circuit enables device dimensions on the millimeter scale, such as less than 10 mm x 10 mm, to be achieved.
- the electronic frequency filter 38 is employed and selectively attenuates the detected radiation signal 44.
- the value article 16 is provided that includes the luminescent material, and the value article 16 is introduced into the interrogation zone 20.
- the presence of the value article 16 is detected and emission of modulated light 40 by the exciting light source 28 is initiated upon detection of the presence of the value article 16.
- alight source trigger receiver 29 may be present to communicate the presence of the value article 16 and to provide the control signal to the excitation source driver 27, with emission of the modulated light 40 initiated upon sensing the presence of the value article 16 in the interrogation zone 20 or upon sensing of the value article 16 passing into the inlet of the article path.
- the luminescent material ofthe value article 16 is exposed to the modulated light 40 that is produced by the exciting light source 28 at the predetermined modulation frequency. After passing through the optional opticalfilter 37, filtered radiation 43 is detected that includes emitted radiation from the luminescent material.
- the filtered radiation 43 is detected using the photodetector 30 to produce the detected radiation signal 44, and the detected radiation includes all radiation that is passed through the optional opticalfilter 37 including radiation from sources other than the luminescent material (e.g., sunlight, artificial light, or other ambient light sources). Additionally, the photodetector 30 is positioned to receive modulated light 40 from the exciting light source 28 that is reflected from the value article 16, and the radiation that is detected by the photodetector 30 further includes the modulated light 40 from the exciting light source 28 that is reflected from the value article 16.
- sources other than the luminescent material e.g., sunlight, artificial light, or other ambient light sources.
- Portions of the detected radiation signal 44 that are at the predetermined modulation frequency are selectively attenuated with the electronic frequency filter 38 to produce the filtered electronic signal 46, and the filtered electronic signal 46 is amplified with the amplifier 48 to produce the amplified electronic signal 52.
- the amplified electronic signal 52 is provided to the circuitry 50 to convert the amplified electronic signal 52 or data derived therefrom to the authentication output.
- the authentication output is indicative of authenticity of the value article 16.
- the output of the circuitry 50 may be a logical value of “1” as long as the amplified electronic signal 52 value remains above a predetermined intensity value, and the output value may be employed by the authentication system 10 to conduct further functions based upon authentication of the value article 16.
- a second embodiment of electronically manipulating the detected radiation signal 44 using the signal manipulation circuit 238 will now be described with reference to FIG.3.
- the luminescent material is exposed to light 40 produced by the exciting light source 28 and the signal manipulation circuit 238 is a squelch circuit. All other features of the authentication device 114 of this embodiment may be the same as those described above unless indicated otherwise.
- the detected radiation signal 44 is electronically manipulated by electronically blocking the detected radiation signal 44 with the squelch circuit 238 until production of light 40 from the exciting light source 28 is ceased.
- the squelch circuit 238 effectively shorts out the detected radiation signal 44 prior to amplification in amplifier 48.
- the squelch circuit 238 may electrically short the detected radiation signal 44 when the squelch circuit 238 is closed, although it is to be appreciated that embodiments are possible where the squelch circuit 238 shorts the detected radiation signal 44 when open.
- electronic blocking of the detected radiation signal 44 by the squelch circuit 238 also ceases, thereby allowing the detected radiation signal 44 to be amplified to produce an amplified electronic signal 52 in the same manner as described above.
- electronic blocking of the detected radiation signal 44 by the squelch circuit 238 also ceases as soon as possible after production of light 40 from the exciting light source 28 is ceased for purposes of detecting intensity of tail emissions from the luminescent material over time. Once electronic blocking of the detected radiation signal 44 ceases, saturation of the detected radiation signal 44 by the light 40 from the exciting light source 28 is no longer a concern during amplification.
- Voltageof the amplified electronic signal 52 can then be converted to an authentication output in the same manner as described above. It is to be appreciated that, although not shown, amplification of the detected radiation signal 44 may also be conducted prior to electronic blocking by the squelch circuit 238.In this regard, the squelch circuit 238 may be positioned between amplifiers when multiple amplifiers are employed, provided that the squelch circuit 238 is at least positioned prior to a final amplifier 48 that produces the amplified electronic signal 52 that is converted to the authentication output. [0037] Referring to FIG. 4 with continued reference to FIG.
- the amplified radiation signal 52 as illustrated in FIG. 4 enables a determination of decay time constant (Tau).
- Tau decay time constant
- the intensity of the detected radiation signal 44 decays over time, and multiple points on the voltage versus time curve for the amplified radiation signal 52 can be measured or curve fit can be employed to determine the rate of decay for the luminescent material.
- the decay time constant can be represented by the constant IJ (Tau) in the equation:
- FIG. 4 illustrates the tail emission intensity for stationary value articles
- I denotes the emission intensity at time t
- FIG. 4 illustrates the tail emission intensity for stationary value articles
- many applications involve authentication of moving articles (such as in vending machine applications, currency counting applications, and the like).
- emissions from the luminescent material can generally only be detected for very short amounts of time, which does not allow for generation of an intensity versus time curve from which Tau can be determined.
- FIG. 4 illustrates the tail emission intensity for stationary value articles
- pulses of light 40 may be employed in conjunction with the squelch circuit 238 to produce short cycles of excitation/emission from the luminescent material from which Tau can be determined.
- the luminescent material of the value article may be exposed to pulsed light 40 produced by the exciting light source 28 and the detected radiation signal 44 is only electronically blocked using the squelch circuit 238 during production of light 40 from the exciting light source 28.
- FIG. 4 although no lag is illustrated in FIG. 5 between switching off the light 40 from the exciting light source 28 and switching off the squelch circuit 238, it is to be appreciated that a delay generally exists and intervals between pulses of light 40 are generally determined to account for the delay. Referring to FIG. 5 and with continued reference to FIG.
- the pulses of light 40 can be sufficiently close together such that a second pulse occurs while the luminescent material is still emitting radiation due to a first pulse, with the impact being that excitation of the luminescent material can produce an initial emission intensity 45 after the second pulse is ceased that is greater than an initial emission intensity 41 after the first pulse of light 40.
- Tau can be determined by measuring intensity of the emissions from the luminescent material at substantially equal times after the squelch circuit 238 is turned off for both the first pulse and the second pulse of light 40. In this regard, Tau can effectively be determined for moving value articles.FIGS.
- 6(a)-6(c) provide schematic representations showing how emission intensities can be measured after the squelch circuit 238 is turned off for both the first pulse and the second pulse of light 40 when luminescent materials having different Tau values are interrogated for purposes of illustrating how the measured emission intensities vary based upon the different Tau values.
- FIG. 6(a) voltages over time for light 40 including a first light pulse 47 and a second light pulse 49 are illustrated along with corresponding voltages over time for squelch on/off.
- FIG.6(b) illustrates emission intensity of luminescent material having a relatively quick decay rate with emission intensity being measured at points 51 and 53
- FIG. 6(c) illustrates emission intensity of luminescent material having a relatively slow decay rate with emission intensity being measured at points 55 and 57.
- a voltage ratio of point 53 to point 51 is significantly less than a voltage ratio of point 57 to point 55.
Abstract
Description
Claims
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US14/921,564 US10650630B2 (en) | 2014-10-31 | 2015-10-23 | Authentication systems, authentication devices, and methods for authenticating a value article |
PCT/US2015/057980 WO2016069858A1 (en) | 2014-10-31 | 2015-10-29 | Authentication systems, authentication devices, and methods for authenticating a value article |
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EP (1) | EP3213303B1 (en) |
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AU2018242894B2 (en) * | 2017-03-27 | 2020-11-05 | Glory Ltd. | Optical sensor, light detection apparatus, sheet processing apparatus, light detection method, and phosphorescence detection apparatus |
JP6944259B2 (en) * | 2017-03-27 | 2021-10-06 | グローリー株式会社 | Phosphorescence detection device, paper leaf processing device and phosphorescence detection method |
JP6944258B2 (en) * | 2017-03-27 | 2021-10-06 | グローリー株式会社 | Phosphorescence detection device, paper leaf processing device and phosphorescence detection method |
JP7017862B2 (en) * | 2017-03-27 | 2022-02-09 | グローリー株式会社 | Light sensor, photodetector, paper sheet processing device and light detection method |
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EP3213303B1 (en) | 2024-04-17 |
US20160125682A1 (en) | 2016-05-05 |
JP2017534120A (en) | 2017-11-16 |
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US10650630B2 (en) | 2020-05-12 |
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